how to use the flock system call in sun os 5.07 ??

At the time of compilation it gives the error undefinded function flock ....

Are any flags required at the time of linking,.........
awating a reply..
thanx in advance....

File I/O primitives are part of libc on Solaris. So, make sure your object code is linked with libc (with -lc flag) during linking. In general, C/C++ compiler drivers are smart enough to pass -lc to linker. But you better make sure it is being passed by turning on verbose option during compilation (add -v for C++ or -# for C compiler on compile line if you are using Sun Studio compilers)

If you couldn't resolve the issue with -lc, please post the following:
1) Compiler driver being used ie., GCC/Sun Studio/..
2) A small test case which exhibits the behavior you mentioned in your post
3) Compile line, Error messages, etc.,

Flock used to be a SunOS 4 system call but was obsoleted with SunOS 5, so there's not such a system call with SunOS 5.7 (a.k.a Solaris 7) or any SunOS 5 release. There is however a flock BSD compatibility library function, which use is discouraged unless you are porting BSD code.

"Man flock" will tell you more about that, and "man -s 1b cc" will tell you what options you need to add to your compiling and linking commands to be able to use flock, should you insist using it.